Effects of Flood Flows on Habitat Use by Benthic Missouri River Fishes: Toward Improving Capacity for Recovery

Increasing spring flows queue many riverine fish species to initiate spawning behavior.  Low summer flows facilitate growth and recruitment of young fluvial specialists that require main channel habitats to complete their life history.  How fluvial specialists respond to flood flows during the summer rearing period, however, is not well understood.  The period 2003-2011 reflects a range of ecological flows because it includes characteristics of drought and wet climate cycles.  We evaluated trawl data from lower Missouri River during the summer rearing period to determine how native fluvial specialists respond to the range of ecological flow types.  Preliminary results indicate that low summer flows support development and maintenance of appropriate in-channel nursery habitat distributed laterally across the channel profile.  In contrast, fish appeared more clustered in habitats consistent with velocity refuge near the channel margin during summer flood flows.  This work will assist managers in determining appropriate habitat and flow management programs to build ecosystem capacity for supporting recruitment of native fishes in lower Missouri River in light of an unpredictable climate future.